1. Field of the Invention
The present invention relates to an anti-double firing devise for a single firing mode in a tacker, and more particularly the anti-double firing devise comprising an anti-double firing controller coaxially mounted to a firing control plate and a detent located at the proximal end of a connector to latch the anti-double firing controller for preventing a duplicated shot on a same target while a single firing mode is selected.
2. Description of the Related Prior Art
As well known to those skilled in the art, a tacker-nailer, a stapler, and a pinner, which are used in construction and interior works, are pneumatic machines for fastening a wooden article to another wooden article, a wooden article to a plastic article, a wooden article to a steel article, or a wooden article to a concrete article, and are used in various works, such as exterior works and aluminum chassis works.
Generally, as shown in FIG. 1, a tacker comprises a body 1 having a piston and a cylinder installed therein, a cover 2 for providing air to, and eliminating air from, the piston, a magazine 3 loaded with nails, staples or pins, and a guide 4 for launching the nails, a safety device 5 for ensuring safe operation, a latch device 6 for loading the tacker with nails, a bracket 7 for connecting the magazine 3 to a handle grip 8 to obtain the firm structure of the tacker, and a trigger 9 for driving the tacker.
In the above tacker, the trigger 9 is operated to move the piston installed in the body 1, thereby allowing the nails or the staples loaded in the magazine 3 to go through a desired position of an object through the guide 4.
Most of conventional tackers further comprise all or one of continuous and single firing switches and a locking device, or do not comprise any one of them. Further, most of conventional tackers comprise or do not comprise the safety device 5. A single firing operation is performed to obtain a precision work, and a continuous firing operation is performed to increase user's convenience and efficiency. The locking device is used to prevent accidents caused by user's carelessness.
More particularly, with reference to FIGS. 2A, 2B, 2C, and 2D, single and continuous firing methods using a conventional tacker, such as a nailer, will be illustrated. A safety device 5 is provided at the front end of the tacker and is connected to a connector 100, as shown in FIG. 2A, which is installed in the guide 4. If the connector 100 does not move to the rear end of the tacker in the single or continuous firing position, nails are not launched. Thereby, the tacker prevents accidents caused by user carelessness.
In the single firing mode in the conventional tacker, the tacker has an initial position as shown in FIG. 2a. In the above position, a user brings the front tip of the connector 100 of the tacker into contact on a target, and presses the tacker against the target. Then, as shown in FIG. 2b, the connector 100 linearly moves backward to an operating member 10 (in the direction of B), and the rear end of the connector 100 pushes a firing control plate 94, mounted on the lower end of a trigger 92 by an axle pin 96, to the operating member 10 by a designated length.
Thereby, due to the backward movement of the firing control plate 94, a piston valve rod 12, which is protruded from the operating member 10, is pushed into the cylinder of the operating member 10, by a designated length.
Under the above state, when the user pulls the trigger 92, as shown in FIG. 2c, the lower end of the trigger 92 moves in the arched direction of A, with respect to a rotating shaft pin 97 mounted at the upper end of the trigger 92. Then, the firing control plate 94 mounted on the trigger 92 by the axle pin 96 completely pushed back the piston valve rod 12 into the cylinder of the operating member 10. When the piston valve rod 12 is completely stroked into the cylinder of the operating member 10, the nails 11 loaded in the ejection guide are launched forward.
The firing control plate 94 mounted on the lower end of the trigger 92 by the axle pin 96 is operated by the connector 100 to push the piston valve rod 12 into the cylinder of the operating member 10. Therefore, when the trigger 92 is pulled while the connector 100 is depressed on the target, the firing control plate 94 will be rotated with respect to the contacting point of the connector 100 and the firing control plate 94 to push back the stroke of the piston valve rod 12 into the cylinder of the operating member 10 for firing.
In the continuous firing operation using the conventional tacker, in which a user does not fire one tacker pin but fires several tacker pins toward a broad area of an object in a short time, the user presses the front end of the tacker to a target site under the condition that the user pulls the trigger 92, thereby causing the connector 100 to move toward the operating member 10 (in the direction of B) and the tacker pins to be launched. The fundamental principle of the continuous firing operation is the same as that of the single firing operation. However, in the continuous firing operation, the connector 100 does not contact the object first, but is pressed onto the target site of the object under the condition that the trigger 92 is pulled first.
If the number of target sites of an object is three and the target sites are in close proximity, the user pulls the trigger 92 in the continuous firing mode, and presses the connector 100 against one target site of the object, thereby causing one nail to be launched toward the first target site of the object. Then, the user moves the tacker to another target site of the object under the condition that the trigger 92 is pulled, and presses the connector 100 against the target site of the object, thereby causing other nails to be continuously launched toward the second and third target sites of the object.
In the conventional tacker in the single firing mode, when the connector 100 contacts the target site and the trigger 92 is pulled, a nail is launched onto the target site and the valve rod 12 is pressed again due to the repulsive force of the connector 100 in the same manner as the continuous firing mode. When the valve rod 12 is pressed, the tacker, which should be fired once, is fired twice, thereby causing a difficulty in precisely performing the single firing mode.